I run Win7 64bit, no issues. WoW is a 32bit program so there will be no difference in allotted memory. I know Ventrilo has a 64bit service, buts its footprint is so small you will never see the difference between it and the 32bit version.

7 64-bit here. No noticeable difference to my performance other than the standard improve you'd see from going to an 2gig XP, 7950gt and 1.8GHz Core2Duo to a 4 gig 7, 460gtx and overclocked Sandy Bridge i5. IE massive, but I wouldn't have any idea if anything would be related to swapping to 7. Zero compat issues with WoW. Mass Effect, however, can suck a big one.

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I think only one program I've ever installed on my Mac that ever listed speed improvements for going to 64bit from 32bit and that was Handbrake, everything else was similar to "64-bit compatible but you shouldn't notice anything but slightly more memory usage."

We live in a society where people born on third base constantly try to steal second, yet we expect people born with two strikes against them to hit a homerun on the first pitch.

Using more than 3GB of RAM should make a noticeable difference if you do any amount of multitasking (personally I raid with 30 firefox tabs open at all times).

My main problem when I first moved to 7x64 (well actually Vista x64) was getting the 64-bit Ventrilo to play ball with whatever screwed up my Realtek audio driver. It eventually mysteriously fixed itself (as far as I can tell I waited 6 months and attempted to install the exact same version of Ventrilo that failed before, on the same system configuration, and it started working).